Adamantane acrylate and methacrylate esters and polymers thereof

ABSTRACT

NOVEL COPOLYMERS HAVING LOW MOLD SHRINKAGE PROPERTIES ARE PREPARED FROM ADAMANTANE ACRYLATE AND METHACRYLATES OF THE STRUCTURE   1-R3,3-(CH2=C(-R)-COO-),5-R1,7-R2-ADAMANTANE   WHERE R IS HYDROGEN OR METHYL AND R1, R2, AND R3 ARE PREFERABLY ALKYL OR CYCLOALKYL RADICALS HAVING 1-20 CARBON ATOMS AND A SECOND POLYMERIZABLE UNSATURATED MONOMER SUCH AS METHYL METHACRYLATE, STYRENE, ACRYLONITRILE, AND VINYL CHLORIDE.

United States Patent 3,639,362 ADAMANTANE ACRYLATE AND METHACRY- LATE ESTERS AND POLYMERS THEREOF Irl N. Duling, West Chester, and Abraham Schneider,

Overbrook Hills, Pa., and Robert E. Moore, Wilmington, Del., assignors to Sun Oil Company, Philadelphia, Pa.

No Drawing. Continuation-impart of application Ser, No. 625,581, Mar. 24, 1967, now Patent No. 3,518,241. This application Mar. 13, 1969, Ser. No. 807,068 The portion of the term of the patent subsequent to June 20, 1987, has been disclaimed Int. Cl. C08f /16 US. Cl. 260-785 11 Claims ABSTRACT OF THE DISCLOSURE Novel copolymers having low mold shrinkage properties are prepared from adamantane acrylate and methacrylates of the structure R2 O-C-C=Cli' where R is hydrogen or methyl and R R and R are preferably alkyl or cycloalkyl radicals having 1-20 carbon atoms and a second polymerizable unsaturated monomer such as methyl methacrylate, styrene, acrylonitrile, and vinyl chloride.

This application is a continuation-in-part of Ser. No. 625,581 filed Mar. 24, 1967 now US. Pat. 3,518,241.

This invention relates to copolymers of unsaturated esters containing an adamantane nucleus and more particularly to alkyland/ or cycloalkyl-substituted adamantyl esters of acrylic acid or methacrylic acid wherein the adamantane moiety has 1-4 alkyl and/ or cycloalkyl substituents.

The cage-like structure of the adamantane nucleus has been illustrated in several ways, of which the following is one example:

As can be seen, it consists of three condensed cyclohexane rings arranged so that there are four bridgehead carbon atoms which are equivalent to each other. In view of these bridgehead carbon atoms, dehydrogenation to form an olefinic double bond within the nucleus cannot occur, and hence the nucleus tends to exhibit good thermal stability.

Numerous types of adamantane derivatives have been disclosed in the prior art and a comprehensive tabulation thereof has been presented by Stetter, Angew. Chem. (English ed.), 1 (6), pp. 286-298 (1962). However, acrylate and methacrylate esters containing the adamantane nucleus do not appear to have been made heretofore.

The present invention is directed to and provides copolymers of esters of acrylic acid and methacrylic acid which esters contain one adamantane nucleus per molecule. More specifically, these esters correspond to the formula AOill=CH2 wherein R is hydrogen or methyl depending upon whether the esters are derivatives, respectively, of acrylic acid or 3,639,362 Patented Feb. 1, 1972 "ice wherein R is hydrogen or methyl, R and R are radicals having 0-20 carbon atoms selected from the group consisting of hydrogen, alkyl and cycloalkyl, and R is an alkyl or cycloalkyl radical having 1-20 carbon atoms. In this preferred class of adamantane components, the adamantane nucleus thus has one, two or three hydrocarbyl substituents located at bridgehead positions, which substituents are alkyl, cycloalkyl or combinations thereof.

The above-defined acrylate and methacrylate esters are useful as monomers for preparing solid polymers which can be either homopolymers or copolymers with other vinyl monomers. Such polymers can be made by polymerizing or copolymerizing the foregoing esters by free radical catalysis in conventional manner.

The presence of the bulk adamantyl groups along the polymer chain gives extraordinarily high glass transition temperatures for the homo-polymers and copolymers and imparts high temperature stability characteristics as discussed hereinafter.

'Briefiy stated the present invention is a copolymer comprising repeating units of moieties derived from an unsaturated ester having the formula A-0 i( 3=0H2 and a second polymerizable unsaturated monomer, wherein R is hydrogen or methyl and A is an adamantane moiety having 1-4 substituents on the adamantane nucleus which substituents are alkyl or cycloalkyl radicals having 1-20 carbon atoms, the carboxyl group being attached to A at a bridgehead carbon atom.

The monomer esters can be prepared by esterifying acrylic or methacrylic acid, or more preferably their acid chlorides, with an adamantyl monool or the formula AOH where A is as above defined and the hydroxyl group is attached to A at a bridgehead position. Substituted adamantyl monools or alcohols for making the prepared esters correspond to the formula wherein the several R groups are as previously defined. These alcohols, in which all alkyl groups are at bridgehead positions, can be prepared from mono-, dior trialkylated adamantane hydrocarbons corresponding to the alkyl or cycloalkyladamantyl moiety desired in the product. While the number of carbon atoms in each alkyl or cycloalkyl group can vary widely ranging up to 20, it is usually preferable that these groups be methyl and/or ethyl since the parent hydrocarbons corresponding thereto are more readily obtainable. Thus the alkyladamantyl moiety, i.e.,

desirably is selected from the following: l-methylada- 1o mantyl; 1,3-dimethyladamantyl; l-ethyladamantyl; 1- methyl-3-ethyladamantyl; 1,3,5-trimethyladamantyl; and 1,3rdimethyI-S-ethyladamantyl.

The adamantyl alcohols used for making esters accord- 2O foregoing but having higher alkyl and/or cycloalkyl radicals in place of one or more of the methyl or ethyl substituents.

7 Preparation of the parent hydrocarbons corresponding to alkyl or cycloalkyladamantane moieties as above specified can be carried out by aluminum halide or HP- B'F catalyzed i-somerization of saturated tricyclic hydrocarbons, as disclosed by Schleyer et al., Tetrahedron Letters No. 9, pps. 305309 1961) and Schneider et al., JACS, vol. 86, pp. 5365-5367 (1964), and in US. Pat. Nos. 3,128,316 and 3,275,700. Higher alkyl or cycloalkyl groups can be substituted on the admantane nucleus by a Wurtz synthesis involving reacting bridgehead chloro- 55 or bromoadamantanes with alkali metal alkyls or cycloalkyls in the manner disclosed by Spengler et al., Erdol and Kohle-Erdgas-Petrochemie, vol. 15, pp. 702-707 (1962). Other procedures of making alkylor cycloalkylsubstituted adamantanes are described in Schneider United States application Ser. No. 613,443, filed Feb. 2, 1967, now US. Pat. No. 3,382,288, and in an article by Hock et al., 85 (1966), Recueil 1045-1053. The alkylated adamantanes can, for the present purpose, have either non-branched or branched alkyl groups and can have one or more cycloalkyl radicals in the alkylation moiety with the total number of carbon atoms in each group substituted on the adamantane nucleus ranging up to twenty. Preferably these substituents contain no tertiary hydrogen atoms. Y

It is also preferable that at least one of the R and R groups be alkyl or cycloalkyl so that the substituted ada mantyl moiety will contain not more than one unsubstituted bridgehead position. This renders the product less susceptible to oxidation. For best oxidation resistance both R and R are alkyl or cycloalkyl groups so that the nucleus has no tertiary hydrogen substituent.

The starting alkylated adamantane hydrocarbon is first converted to a l-monool for use as reactant in preparing the present esters. One manner of effecting such conversions is by air oxidation of the parent hydrocarbons at, for example, 160 C. in the presence of a metal salt oxidation catalyst, as disclosed in Schneider United States application Ser. No. 395,557, filed Sept. 10, 1964, now US. Pat. No. 3,356,740. In the oxidation monools form first and these will subsequently convert to diols if the reaction is allowed to continue too far. Some amounts of ketones are also formed during the oxidation. Production of the monools can be maximized by stopping the oxidation before 70% conversion has been reached.

Another way of preparing l-monools of the substituted adamantanes is by reacting the latter with an acetic acid solution of chromic acid, as disclosed in Moore, United States application Ser. No. 421,614, filed Dec. 28, 1964, now abandoned. By using a relatively low mole ratio of Cr to hydrocarbon such as 3:2 good yields of the monool can be obtained.

Preparation of the ester product can be accomplished by known esterification methods. One method comprises refluxing a mixture of acrylic or methacrylic acid and the alkyladamantyl alcohol dissolved in a suitable solvent such as benzene, toluene or heptane and in the presence of an esterification catalyst such as p-toluene sulfonic acid, and trapping out water from the reflux condensate as the esterification reaction proceeds.

The preferred esterification procedure involves reacting the alkyladamantyl alcohol with acrylyl or methacrylyl chloride in accordance with the following This reaction is carried out by dissolving the alcohol in a hydrocarbon solvent, such as benzene, toluene, hexane, heptane or the like, adding a tertiary amine to the mixture in molar excess relative to the alcohol, and then slowly adding the acid chloride thereto. The amine used preferably is triethylamine, although other tertiary amines 0 such as pyridine, tributylamine, -N,N,N',N'-tetramethylethylenediamine, triethylenediamine, picolines, quinoline and the like can be employed. Upon addition of the acid chloride, the initial reaction that takes place involves the formation of a complex between it and the amine. This reaction is exothermic and the complex precipitates as it' is formed. Slow addition of the acid chloride is continued preferably until the amount added is in molar excess of the alcohol. The resulting slurry is then stirred at a temperature in the range of 10-65 C., more preferably 20-60 C., to effect the esterification reaction. A temperature above 65 C. should be avoided as this tends to cause a messy reaction, and it is most preferable to maintain the temperature at 4050 C. Time required' for completion of the reaction will depend upon the reaction temperature used but generally is in the range of 1-20 hours.

As the reaction occurs the amine-acid chloride complex is replaced by an arnine-HCI complex which is also insoluble in the hydrocarbon solvent. The alkyladamantylacrylate or methacrylate product on the other hand remains in solution. After completion of the reaction, the mixture is filtered to remove the amine-HCl complex and the solvent is removed by evaporation. The crude product ester obtained as residue is a reddish liquid. This can be purified by vacuum distillation, after addition of a polymerization inhibitor such as hydroquinone or bis(2-hydroxy-3-t-butyl 5 methylpl1enyl)methane, to give a sweet smelling, colorless liquid as the desired ester product.

The alkylated adamantane acrylates and methacrylates prepared as above described can be polymerized or copolymerized in conventional manner by free radical catalysis using a free radical initiator such as hydrogen peroxide, benzoyl peroxide, dicumyl peroxide, di-t-butylperoxide or azobisisobutyronitrile. Procedures for polymerizing and copolymerizing acrylates and methacrylates are well known and need not be elaborately described here. Discussion of such procedures and of numerous uses of the resin products are given in Encyclopedia of Chemical Technology, vol. 1, 2nd ed. (1963), pp. 303- 311, and similar procedures are applicable here for preparing polymers and copolymers having analogous uses. The present acrylates and methacrylates can be polymerized alone or together, or can be copolymerized with other unsaturated monomers, e.g., ethylene, propylene, butadiene, vinylcyclohexene, dicyclopentadiene, vinylacetate, acrylonitrile, methacrylonitrile, styrene, OL- methyl or u-chlorostyrene, vinylchloride, vinylidene chloride, methacrylate, methylmethacrylate, vinylpyrrolidone, vinylpyridine, maleic anhydride, and methyl or ethyl vinyl ether and the like.

The polymerization or copolymerization reaction preferably is carried out employing a solvent such as benzene or toluene at elevated temperature such as 50- 80 C. The acrylate or methacrylate monomer is dissolved in the solvent, a small amount such as 0.05-0.5% of the free radical initiator is added to the mixture, the mixture is degassed and then heated to and maintained at the selected temperature level until the desired degree of polymerization has been attained. The polymer, which remains in solution, can then be recovered in conventional manner by adding an antisolvent such as methanol, separating the precipitated polymer and drying.

The polymerization also can be carried out without a solvent, and the polymer in such case usually will be cross-linked and at least partially insoluble in organic solvents. Consequently such bulk polymerizations are generally applicable where the polymer is to be produced in the form desired for use, for example, as a cast form or sheet. In carrying out these polymerizations a suitable free radical initiator, such as benzoyl peroxide or ambisisobutyronitrile, is dissolved in the alkyladamantylacrylate or methacrylate, the mixture is degassed and polymerization conditions are established by heating to say 60 C. or by the application of ultraviolet light at room temperature. Polymerization with cross-linking readily occurs, giving a hard glassy polymer. Use of the present monomers in place of conventional acrylates or methacrylates in such bulk polymerizations can be distinctly advantageous in that substantially less shrinkage occurs. For example, with methyl methacrylate 25-30% shrinkage may occur, whereas for the copolymers 7-18% shrinkage is typical.

The acrylate and methacrylate monomers of the present invention can also be polymerized to high molecular weight polymers by means of anionic catalysts. This kind of catalysis for making polymers and copolymers from other types of acrylates and methacrylates has been described in various literature references and similar conditions for anionic polymerization of the present monomers can be used. Examples of anionic catalysts which have been employed are: Grignard reagents such as alkyl or phenyl magnesium bromide (Garrett et al., JACS, 81, 1007-1008 (1959), and Gaylord et al., Linear and Stereospecific Addition Polymers, 531 (1959)); butylithium or fiuorenylsodium (Graham et al., JACS, 82, 2100-2103 (1960)); sodium naphthalene (Graham et al., J. Poly. Sci., 44, 411-419 (1960)); and lithium dispersions (Miller et al., JACS, 80, 4115-4116 (1958)).

Resins containing the alkyladamantyl or cycloalkyladamantylacrylate or methacrylate moieties of the present invention have extraordinarily high glass transition temperatures by virtue of the bulky adamantyl groups appended along the polymer chain. These resins accordingly have high softening points permitting their use at relatively high temperatures and they also have high surface hardness characteristics. Further they have high refractive indexes and, thus, are particularly useful as optical lens material.

The unusually high glass transition temperatures (T of the present polymers and copolymers can be seen by comparison with T values reported in the literature for conventional polyacrylates and polymethacrylates. Typical T values for conventional polymers are given in Encyclopedia of Chemical Technology, loc. cit., p. 308, and by Krause et al., J. Poly. Sci., 3, 3573-3586 (1965). For polyacrylates made from various alkyl esters, these references show T values ranging from C. (for n-octyl) to 94 C. (norbornyl). In comparison, T values found for our homopolymers made from the bridgehead acrylate of 3,5-dimethyladamantanol-1 typically are 107 C. Further, the prior art shows T values for polymers of alkyl methacrylates ranging from 20 C. (butyl) to C. (3,3,S-trimethylcyclohexyl) whereas typical T values for our polymethacrylate products derived from 3,5-dimethyladamantanol-1 are 190-198 C.

The eflect of the adamantyl moiety has likewise a similar effect in the copolymer composition. For example, polymethyl methacrylate (PMMA) has a T of 115 C. whereas a methyl methacrylate-dimethyl adamantane methacrylate (mole ratio 52:45) copolymer has a T of C. 'In order to achieve the full benefit from the copolymers of the present invention such copolymers should contain at least 5 wt. percent up to about 95 wt. percent of the adamantane derived moiety, more prefera bly 20 to 90 wt. percent.

Still another advantage of resins of the present invention results from the stability of the adamantane nucleus as mentioned above. Ester groups made from conventional alcohols of two or more carbon atoms can undergo thermal decomposition by transfer of a hydrogen atom from the beta position of the alcohol-derived moiety in the following manner:

This type of decomposition results, as shown, in the conversion of the ester group to a carboxylic acid group and an olefin. While prior art acrylate or methacrylate resins can undergo this type of decomposition at high temperature, resins made from the present ester products cannot as this would require the formation of a double bond in the adamantane nucleus which, as previously stated, cannot occur.

The following examples will illustrate the invention:

EXAMPLE 1 This illustrates the preparation of 3,5-dimethyl-l-ada mantylacrylate by the reaction of 3,5-dimethyl 1 adamantanol (DMAO) with acrylyl chloride. 10 g. of DMAO (0.055 mole) were dissolved in a mixture of 75 ml. of benzene and 5 ml. of pyridine (0.062 mole). Acrylyl chloride in amount totaling 5.4 g. (0.06 mole) was added dropwise over a time of 0.5 hour while the mixture was stirred and cooled. A complex between the acrylyl chloride and pyridine precipitated, forming a slurry. The mixture was stirred for 6 hours at room temperature to complete the reaction. The pyridine-HCl complex that had been formed was separated by filtering the mixture, and solvent was evaporated from the filtrate leaving a reddish liquid residue. This was shown by vapor phase chromatography and IR analysis to be mainly 3,5-dimethyl1-ada mantylacrylate. To the crude product was added a small amount of a polymerization inhibitor, viz bis (2-hydroxy- 3-t-butyl-5-methylphenyl)methane, and the mixture was then vacuum distilled to give 6 g. of pure 3,5-dimethyll-adamantylacrylate. This product was a colorless, sweetsmelling liquid having the following properties:

Density, 20/4 1.0255 Refractive index 1,4873 Refractive dispersion at 20 104 Hydrogen red line 1.4847 Hydrogen blue line 1.4951 KV at 100 F., cs. 7.2

EXAMPLE 2 The same ester as in Example 1 was again prepared but using acrylic acid instead of the acid chloride. A solution of 12.01 g. of acrylic acid and 9.98 g. of DMAO (acid: alcohol molar ratio=3:1) in 250 ml. of toluene was prepared and 0.5 g. of ptoluene sulfonic acid was added as esterification catalyst. The mixture was then refluxed and water formed in the reaction was trapped out of the condensate. After 28 hours 0.5 g. more of the catalyst was added and refluxing was continued for a total time of 72 hours. The reaction mixture was then washed with aqueous Na CO and dried, and the solvent was evaporated. The residue was distilled and a fraction (5.12 g.) of substantially pure 3,5-dimethyl-adamantylacrylate having essentially the same properties as given in Example 1 was obtained.

Comparison of reaction times for Examples 1 and 2 shows that esterification of the DMAO is more readily achieved by using the acrylyl chloride rather than acrylic acid.

EXAMPLE 3 In this example DMAO was reacted with methacrylyl chloride to produce 3,5-dimethyl-l-adamantylmethacrylate. More specifically 27 g. (0.15 mole) of DMAO were dissolved in 200 ml. of benzene, 65 ml. (0.47 mole) of triethylamine were added and 30 ml. (0.31 mole) of methacrylyl chloride were added dropwise to the mix ture while cooling and stirring. The mixture was then stirred overnight to insure completion of the reaction. Triethylamine and HCl formed were removed by washing the mixture successively with water, aqueous NaOH Refractive index (20/D) 8 EXAMPLE 4 This example illustrates the preparation of polymer from 3,5-dimethyl-l-adamantylacrylate. The reaction was carried out in a dried container which had been carefully purged with nitrogen to exclude air. The reaction mixture consisted of 1.0 g. of the acrylate product prepared in Example 1 and 5 ml. of benzene to which had been added 0.003 g. of benzoyl peroxide as a free radical initiator (0.3% by weight based on the monomer). The mixture, was heated to and maintained at 65 C. for 16 hours,

resulting in a viscous solution of polymer in benzene. I

This solution was poured into absolute methanol to precipitate the polymer, which was separated, dried and pulverized to yield a white amorphous powder. Properties of this poly (dimethyladamantylacrylate) product were as follows:

EXAMPLE 5 A series of polymerization runs was made with 3,5- dimethyl-l-adamantylacrylate as the monomer, benzene as solvent and a reaction temperature of about 60 C. In each run a solution of 1.0 g. of the monomer in 4-5 ml. of benzene containing a small amount of initiator was prepared and the mixture was degassed by freezing and evacuation. The degassed mixture was heated under nitrogen to about 60 C. and maintained at that temperature for times as shown in Table 1. In Run Nos. a-e, the initiator was benzoyl peroxide (designated BP) and in Run Nos. 1 and g, azobisisobutyronitrile (AIBN), the proportions of initiator being shown in Table I. After the reaction the polymer was precipitated from solution, separated and dried. Typically the polymer thus obtained in a white powder which when heated and molded gives a clear, colorless article. Also typically, all of these polyacrylates have glass transition temperatures (T,;) of 100 C. or above.

TABLE I.-PREP.ARATION OF POLY(DIMETHYLADAMANTYLACRYLATES) Reaction Polymer Run Imtiator time, yield, R.I., Inherent Density, M.P., C. T No. (percent) hrs. percent 20/D viscosity 1 20/4 (capillary) C.

(0.12) 64 72 0. (0. 24) 17 73 1.502 (0. 26) 19 G8 1. 508 1. 04 (0. 36) 19 1. 496 0. 1.02 290 d. (softens 170)-- (0.37) 17 71 1.496 0. d. 245 (0.14) 66 98+ 0. 1. 09 (0. 08) 40 98+ 0. 44

l in benzene at 100 F. and concentration of 0.5 g./10O ml. of benzene.

and water, following which the mixture was dried over EXAMPLE 6 M 80 A small amount of free radical inhibitor was added, the solvent was distilled off and the reaction product was then vacuum distilled to recover the methacrylate ester. This product was a colorless liquid having a slight sweet odor and the following properties:

Another series of runs was made in generally the same manner as in the above series except that a methacrylate monomer was used, viz. 3,5-dimethy1-1-adamantylmethacrylate, prepared by the procedure of Example 3. All of the polymer products were white powders and when Density, 20 /4 1.004 molded into discs gave clear, colorless articles. Results Refractive index, 20/D 1.4890 are given in Table II.

TABLE lL-PREPARATION OF POLY(DIMETHYLADAMANTYLMETH- ACRYLATES) Polymer Run Initiator Reaction yield, 11.1., Inherent Density, Tg, No. (percent) time, hrs. percent 20/D viscosity 1 20/4 C h. BP (0.20) 44 20 0. 55 190 t AIBN (0.10 45 0.65 178-193 J IBN (0.10 88 62 1.508 0.89 1.052 197-190 k AIBN 0.00 40 71 0.90 1. 046 196 z AIBN (0.10 71 0.86 1.014 204 1 In benzene at F. and concentration of 0.5 g./100 mi. of benzene.

The following examples relate to the various and diverse copolymers of dimethyladamantyl methacrylate (DMAMA) methyl methacrylate, styrene, acrylonitrile and vinyl chloride respectively. In the examples the methyl methacrylate, styrene and acrylonitrile employed were the constant boiling fraction from commercial materials having 98% purity as shown by gas chromatography. The vinyl chloride was employed directly from a commercial gas cylinder (Matheson, Coleman and Bell Co.). The DMAMA was prepared as shown in Example 3. After the distillations, the purified DMAMA was stored in Dry Ice until used. The purity was always at least 98%. The poly(dimethyladamantyl methacrylate) (PDMAMA) used as a comparison is that designated in Run No. k of Table II in Example 6.

Various evaluation procedures were used in determining the relative merits of the DMAMA copolymers relative to the relevant homopolymers.

(1) Inherent viscosities All viscosities were obtained at a concentration of 0.5 g./dl. at 100 F. Duplicate runs were made and flow times were reproducible within 0.2 second. Inherent viscosity is represented by the equation:

Irelntive 1inherent where "relative t =fiow time through a viscometer of a liquid reference t=fiow time through the same viscometer of dilute solution of polymer in the reference liquid c concentration of polymer in solution expressed in rams/ deciliter (2) Molecular weights All molecular weights were obtained by membrane osometry and are number average molecular weights.

(3) Glass transition temperatures These were obtained by one of two methods: differential scanning calorimetry (Perkin-Elmer Model DSC-lB) or differential thermal analysis, the latter being the preferred method in most instances.

(4) Tensile properties Tensile bars were molded and evaluated for stress, elongation, and modulus.

(5) Percent shrinkage This was calculated from the densities of the copolymer and comonomer mix. Copolymer densities were determined experimentally, and the density of a comonomer mix was calculated by assuming a linear dependence of 10 density upon weight fraction. It was found experimentally that refractive index was linear with respect to weight fraction, and hence, it is a valid assumption that density (also a colligative property) would possess the same linear dependence.

(6) Scratch resistance This was determined by scratching the polymer surface with lead pencils of hardness 2H-6H. Scratch resistance was expressed as a value between that which scratchedthe surface and that which did not. 5H S 6H means that a 6H pencil scratched the surface but a 5H pencil did not.

(7) Flow rate for PVC copolymers (8) Degree of polymerization (DP) homopolymer molecular wt. polymer molecular Wt. monomer copolymer molecular wt. copolymer average molecular wt. monomers EXAMPLE 7 This example illustrates the preparation of a copolymer from 3,5-dimethyl-l-adamantylmethacrylate (DMAMA) and methyl methacrylate (MMA) Comonomers, solvent and initiator were charged into a heavy walled 50 cc. polymerization tube which was degassed and sealed oil under vacuum. The tube was placed in a constant temperature bath a C. :0.1 C. for a given time period, then cracked open and the contents diluted with 2 cc. of toluquinone. The solution was poured into excess methanol, and then precipitated. Copolymer was filtered, dried, and weighed to determine percent conversion. It was then purified by redissolving in benzene and reprecipitating from methanol twice. Finally, it was dried in a vacuum oven at 50 C. overnight. The copolymerization data for a number of runs are summarized in Table III.

The polymethyl methacrylate (PMMA) was a commercial grade of powder from Eastman Organic Chemical Company. A comparison of the properties of PMMA, PDMAMA and two copolymer samples is shown in Table IV.

TABLE HL-DMAMA-METHYL METHACRYLATE COPOLYMERIZA'IIONS Solvent: Benzene Initiator: Benzoyl peroxide Run Number 241 A 242 B 246 C 247 D 247 E 251 F 253 G 253 H 254 I 261 262 273 A 273 B 2. 008 1.004 1. 004 2.008 3.012 2.008 1. 004 2.008 6. 43 2. 51 2. 309 1. 406 0. 936 1. 872 2. 808 2. 808 0. 936 0. 468 4. 680 O. 187 3. 56 8. 99 0. 936 0. 936 2.0 3.0 3.0 4. 0 5. 0 4.0 2. 5 6.0 2. 2 10.0 11.5 3.2 2. 3 2.0 3. 0 3.0 4.0 5.0 4. 0 2. 5 6.0 2.2 40 60 3. 2 2. 3 1.5 2. 0 2. 5 2. 3 2.1 2. 0 2.0 2. 5 3.5 64 64 5.0 5. 0 Weight copolymer, g .053 0. 024 0. 167 0. 226 0. 215 0.135 0. 043 0. 521 0.072 4. 3 7. 4 0. 743 0. 486 Yield copolymer, percent 2.7 0.8 5.8 7. 0 4. 5 3. 4 1.7 10.3 3.4 43 64 22. 9 20. 8 Elemental analysis:

0 69. 82 68. 66. 54 65. 58 67. 44 72. 81 73. 64 63. 78 74. 52 72. 12 64. 27 73. 50 71. 41 H 9. 18 9. 15 8. 73 8. 54 8. 70 9. 52 9. 52 8. 52 9. 58 8.93 8. 52 9. 49 9. 07 0 21. 00 21. 24. 73 25. 88 23. 86 17. 67 16.84 27. 70 15.90 18. 95 27.21 17. 01 19. 52 DMAMA in copolymer, weight percent 0.57 0.49 0. 38 0.32 0.44 0. 74 0.79 0.22 0. 84 0. 69 0. 25 0.78 0. 66

a Monomers were charged volumetrically. Using a 1.0 cc. plpet to charge monomer and calculating the weight by means of the density, rather than weighing directly results in an experimental error of less than 1%.

b Determined from C,H analysis by difference.

Norn.B=Bireringent.

The copolymers exhibit higher T than PMAA and are at TABLE IV.-COPOLYMER PROPERTIES: DMAMA-MMA Property PMMA PDMAMA 261 202 7 Weight fraction DMAMA (0. (1. 00) 0. 70 0. Mole fraction, ISMAMA-.- 0. 00 1. 00) 0. 48 0.12 y ns(Benzene, 100 F.) 0.96 0.90 l. 24 l. 17 l 345, 000 348, 000 204, 000 144, 000 D.P 3, 450 1, 400 1, 000 1, 050 Tg, 0. (D 115 190 155 128-130 Refractive index 11)").-. 1. 490-1. 494 1. 508-1. 512B 1. 506-1. 510B 1 494%. 498B Density 1. 17 1. 046 1. 05 1 9 Shrinkage, percent.-.. 24 4 7 18 Shore D hardness...-. 89 83 2 83-84 Scratch resistance, S 6H 5H S 6H 5H S 0H H Disc clarity Tensile properties:

Stress, p.s.i 7, 780 5750 Elongation, percent. 3. 5 2. 7 Modulus, p.s.i 295,000 347, 000

1 Calculated: 1]=6.74X10' M.". [W. R. Moore and R. J. Fort, J. Polymer 801., A1, 920

1 Sample cracked at -78. I Excellent.

TABLE VI-C0ntinued least as stable to thermal decomposition (to -300 C.). Property Polystyrene PDMAMA 276 The shrinkage of the copolymers upon polymerization is 1, 540 1, 400 1, 040 an lmprovement over PMMA. 103 190 121 1. 580-1. 5 0 1. 508-1. 5121; 1. 558-1. 302 EXAMPLE 8 04 i3 83 This example illustrates the preparation of a copolymer Disc clan-W 2 3H s 4g from 3,5-dimethyl-l-adamantyl methacrylate and styrene. Tensile properties: 100 5 000 The same procedure as in Example 7 was followed and f,;, ;f;f; gg; "'j j "I: 1.28 the results are shown in Table V. 30 Modulus, p.S.l 259, 000 240, 000

The polystyrene was prepared under the same procedure 1 C 1 1 t d f t b t 300 C 3. C11 0. e F0111 ViSCOSi' y in enzene & 1 and coqdltlons as the PDMAMA and the copolymers A ['11]=9.7 10- M- 77:0.69 [Styrene, R. H. Boundy and R. F. companson of PDMAMA, polystyrene and one copoly- Boyer, ea. 1952 p. 334.] mer is shown in Table V. Excellent 5 TABLE V.DMAMA-STYR ENE COPOLYMERIZATIONS The T3 offhe copolymer was W to where So1vent Bemene molded artlcles would be heat stenlrzable and at the same Initiator: Benzoyl Peroxide time, mold shrinkage is reduced. Surface hardness is 1m- Run number 26H 26H 26M 26M 26% 276 proved (copolymer exh1b1t1ng greater surface hardn ss 40 than elther homopolymer). 01 3 lzMAMA,g 5.1 1% 3. 2 .3 2 3.030 5.020 4.02

eg 8 yrene g .9 6 0.453 7.25 XAMT Weight initiator, mg- 4.0 4.0 3.0 0.0 5.5 12.4 E LE 9 Volume solvent, co.- 4.0 4.0 3.0 6.0 5.5 12 Wililiglll'l, hlrs 0 2 3 3. 2 3.1 0 3.8 0 3.8 22 [his example lllustrates the preparatlon of a. copolymer eg copo ymer g 1 .469 .580 2.0 Yield co olymerybercenhnu 0 4 4 7 9 10.6 18 from 3,5 dlmethyl l adamantyl methacrylate and acrylo LR. ena ysis, weight percent n1tr1le. The same procedure as 1n Example 7 was followed. g f' fig (L28 M2 0 76 45 In the purification procedure, however, several of the co- DMAMA 25 0.78 0.00 0.84 0.90 polymers were dissolved in dimethylformamide (DMF) iii ifi $$Zi$2i and precipitated from methanol. All samples were dried in DMAMA 0.27 0.70 0.00 0.88 0.80 0.43 a vacuum oven at 50 C. to constant weight to insure Charged vommetricmm 50 solvent removal. Copolymenzatron data 18 summarized 1n Table VII. TABLE VL-COPOLYM R PROPERTIES: DMJAMA- The Polyacrylonitrfle Was P p y the 8mm STYRENE method as the copolymers, however, because of the in- Property polystyrene PDMAMA 276 tractible nature of PAN and the resulting difliculties in molding some of the values thereof in Table VII are Weight fraction, DMAMA- (0. 00 1.00 43 Mole fraction, DMMAuu 0.00 1.00 0 59 from the llterature. Table VII shows a companson of the 1 .1 (benzene. 100 0483 properties of PAN PDMAMA and three samples of co- Mn 1 100,000 348,000 272,000 polymer TABLE VIL-DMAMA-ACRYLONITRILE COPOLYMERIZATIONS Solvent: N ,N-Dimethyl Acetamide (DMAC) Initiator: Benzoyl Peroxide Run number 279-1 280-0 280-3. 280-S 281-1 284-U 284-X 298 510 Weight DMAMA,g 1.004 3.012 1. 004 1.004 4.010 1.004 3.012 3.012 wei ht eerylonitrile,g 0.800 0.800 2.418 1.012 0.403 4.830 0.806 13. 702 2421 Weight initiator, mg--- 2.0 4.0 3.4 2.0 4.5 5.8 4.0 10.7 3.1 Volume solvent, cc- 2. 0 4. 0 4. 0 3. 0 4. 5 7. 0 4. 0 20 25 erun,hrs-... 4 4 2.3 2.0 2.0 2.0 2.0 7.0 18 Weight copolymeng..- 0.2 0.8 0.254 0.18 0.90 0.42 0.53 3.5 14.7 Yield eopolymer, percent- 21 7. 4 6.9 20 7. 2 13.8 21 63 Purification solvent Benzene Benzene DMF Benzene Benzene DMF Benzene DMF DMF Elemental analysis:

cen 0.77 0.87 0.63 0.68 0.94 0.46 0.80 0.45 01 I Charged volumetrlcally.

b The material in the polymerization vessel had become a hard rubbery White mass. Soluble polymer was extracted by treatment with DMAO and DMF.

ee. Calculated from nitr en analysis TABLE VIIL-COPOLYMER PROPERTIES: DMAMA-ACRYLONITRILE Property PAN PDMAMA 298-ANC l 298 510 Weight fraction, DMAMA (0.00) (1. 0. 0. 45 0. l6 Mole fraction, DMAMA (0. 00) (l. 00) 0. 44 0. 15 0. 04 li nh (DMF, 100 F.) 0. 68 Z 0. 90 1. 1. 26 l. 03 Mn a 20, 200 343, 000 517, 000 50-100, 000 50-100, 000 v D-P 550 1, 400 -2, 300 350-700 600-1, 200 Tg, C. (DTA) 98 196 136-155 110 (115) Refractive index (1113 4 1.518 1.508-1. 512B 1.5141.518 1. 530-1. 534 1.518 1. 522B Density 5 1. 17-1. 18 l. 040 1. 064 1. 076 1. 130 Shrinkage, percent 4 Shore D hardness 83 86-7 75-8 68.83 Scratch resistance, 5H S 6H 5H S 6H 5H S 6H 6H Molding temperature, C- 220 170 120-150 150 Color of molded specimen Clarity of molded specimen l Blend of run Nos. 280-Q, 281-1 and 284-X. 2 Determined in benzene at 100 F 3 Calculated from viscosity in DMF: [q]=31.7X10' MU". [Polymer Handbook, J. Braudrup and E. H.

Immerg'ut, ed. p.1v-23.]

4 R. Chaing, J. Polymer Sei., A1 2765 (1963).

Kobayashi, Bull. Chem. Soc. Japan, 726 (1962). ear.

7 Yellow. 5 Excellent.

The color of the copolymers was considerably improved over PAN which is yellow to brownish color prior to heating and upon heating darkens. The copolymers are fine white powders that molded easily. Copolymers containing at least 50 wt. percent DMAMA (18 mole percent) are completely colorless when molded and have excellent clarity. The copolymer of only 15-20 wt. percent DMAMA (-5 mole percent) was slightly yellow after molding, but still possessed good clarity.

The solubility characteristics of the copolymers were also improved over PAN. Copolyrners containing at least 50 wt. percent DMAMA were completely soluble in benzene and other aromatic hydrocarbons. PAN is only slightly soluble in such highly polar solvents as dimethylformamide and dimethylacetamide. Sample 298 containing 15-20 wt. percent DMAMA had a T of 110 C. This sample was easily molded in a clear, thin film, which when stretched to twice its Original length under a heat lamp exhibited a small degree of orientation as evidenced by X-ray analysis. There was considerable improvement in shrinkage over PAN although Shore D hardness for this copolymer (298) was a little lower than other samples. Sample 298ANC although somewhat brittle, yielded upon molding a completely clear colorless material with good Shore D hardness and excellent shrinkage (only 4%) 298-ANC also exhibited the highest degree of solubility in benzene.

EXAMPLE 10 This example illustrates the preparation of a copolymer from 3,5-dimethyl-l-adamantyl methacrylate and vinyl chloride. Copolymerizations were run in small {100 cc.) pressure bottles using Buta N liners and bottle caps. The bottles were wrapped with insulating tape.

The DMAMA, initiator and solvent were charged into the bottle and degassed by the freeze-thaw process. The bottle was flushed with nitrogen, quickly capped tightly, and froze in a Dry Ice bath. Vinyl chloride was condensed directly from a cylinder into the bottle, and as the bottle warmed up, a small amount of vinyl chloride was allowed to escape to produce an added sweep of gases from the polymerization vessel. The bottle was held at 50.0 C. :0.1 C. in a constant temperature bath for a given time period. The excess vinyl chloride was then allowed to escape and the bottle was opened. The solution was poured into methanol and the precip'ated copolymer was isolated as a fine white powder. The copolymers were purified by dissolving in tetrahydrofuran and reprecipitating from methanol twice. All were dried to constant weight in a vacuum oven at 50 C. The copolymerization data is summarized in Table IX.

All of the vinyl chloride copolymers were stabilized be fore molding. (Elemental analyses were obtained before stabilization.) The stabilizer used was a barium-cadmium compound. Advastab BC-103A (Advance Division, Carlisle Chemical Works, Inc.). Concentration used was 2 parts pere hundred by weight, measured volumetrically with a hypodermic needle assuming a stabilizer density of 1.00. In general, 10 drops were equivalent to 0.1 m1, so for very small amounts, the material was measured in drops. The procedure was to slurry the polymer powder in pentane, add the stabilizer, and stir the mixture briskly as the pentane evaporated. The last traces of pentane were removed by heating the copolymer in a vacuum oven at 45-50" C. at least overnight.

The polyvinyl chloride used for comparison was B. F. Goodrich Companys Geon 101. The results of the comparisons are shown in Table IX.

TABLE IX.-DMAMAVIN YL CHLO RIDE C OPOLYME RS Solvent: Chlorobenzene Inmator: Azobisisobutyronltrile Number 519 521 528 520 632 Weight DMAMA,g- 1. 10 1. 2 2. O 3.0 3. 0 Weight vinyl chloride, g 26. 2 25. 4 17. 2 3. 7 1. 5 Weight initiator, g 0. 203 0.18 0. 194 0.377 0.031 Volume solvent, ccb 20 20 20 5 4 Time run, hrs 23 12 6. 5 5. 0 4. 0 Weight copolymer, g 23. 4 6. 5 4. 7 1. 4 1. 5 Yield copolymer, percent. 86 25 24 21 43 Elemental analysis:

C 43. 32 55.81 73. 12 74. 31 5. 51 1. 41 9. 44 9. 71 46. 49 31. 43 6. 34 d 2. 86 O 4.68 11.35 11.10 13.12 DMAMA 1n copolymer, weight percent 0. 18 0. 45 0. 89 0.

B Charged volumetrieally.

b Solvent was oyclohexane.

Calculated from chlorine content. 4 Average of two values.

8 By difierence.

TABLE X.COPOLYMER PROPE RTIES: DMAMAVINYL CHLORIDE V 8 Property PDMAMA PVC 521 529 529 532 Weight fraction, DMAMA- (1. 00) (0. 00) 0. 1S 0. 45 0. 89 0. 95 Mole fraction, DMAMA- (1.00) (0.00) 0.05 0. 17 0. 67 0. 83 lillinh (THF, 30 F.)...- 0. 56 1. 04 0. 47 0. 30 0. 30 0. 39 Mn 239, 000 1 90, 500 24, 300 25, 300 82, 600 61, 300 DP 964 1, 450 253 173 362 256 Tg, C. (DTA)- 190 82 83 93 117 107 Refractive index ("1: 1. 508B 1. 536 1. 536 1. 536- 1. 516- 1 512- Flow rate, relative to PVC 1 0) 3- 9 3 2.8 Color of molded specimen 1 Clarity of molded specimen l Calculated from THF viscosity, [1 ]=219 1O- M-., H. N. Frledlander, L. H. Peebles, Jr., J. Brandru purd, I. R. Kirby, Macromolecules, 1, 79 (1968) 1 Pow properties and properties of molded specimens were determined on stabilized samples at 165 0., 5000 i No fusion. 4 Clear. Green. 1 Excellent. Good.

wherein R is hydrogen or methyl and R and R are radicals having 0-20 carbon atoms selected from the group consisting of hydrogen alkyl and cycloalkyl and R is a radical having 1-20 carbon atoms selected from the group consisting of alkyl and cycloalkyl and a second polymerizable unsaturated monomer.

2. The copolymer according to claim 1 wherein the copolymer contains 5 to 95 wt. percent of the adamantane moiety. 8

3. The copolymer according to claim 2 wherein the copolymer contains 20 to 90 wt. percent of the adamantane moiety.

4. A polymer according to claim 2 wherein the second polymerizable unsaturated monomer is selected from the group consisting of ethylene, propylene, butadiene, vinylcyclohexene, dicyclopentadiene, vinylacetate, acrylonitrile, methacrylonitrile, styrene, a-methylstyrene, a-chlorostyrene, vinylpyrrolidone, vinylpyridine, maleic anhydride, methylvinyl ether and ethylvinyl ether.

5. A polymer according to claim 4 wherein the moiety is selected from the group consisting of l-methyladamantyl, 1,3 dimethyladamantyl, 1 ethyladamantyl, lmethyl-3-ethyladamantyl, 1,3,5-trimethyladamantyl, and 1,3-dimethyl-S-ethyladamantyl.

6. A polymer according to claim 1 wherein the unsaturated ester is an acrylate. Y 7. A polymer according to claim 1 wherein the unsatu rated ester is a methacrylate.

8. A polymer according to claim 4 wherein the unsaturated ester is an acrylate.

- 9. A polymer according to claim 4' wherein the unsaturated ester is a methacrylate.

'10. A polymer according to claim 5 wherein the unsaturated ester is an acrylate.

'11. A polymer according to claim 5 wherein the unsaturated ester is a methacrylate.

References Cited UNITED STATES PATENTS 3,342,880 9/1967 Reinhardt 26089.5

HARRY WONG, JR., Primary Examiner US. Cl. X.R. 

